Control mechanism



April 1962 J- M. REYNARD 3,029,921

CONTROL MECHANISM Filed March 9, 1961 2 Sheets-Sheet 1 Fig.1

l 67 70 2 i I i INVENTOR JOHN M. lawn!) BY a f t MU April 17, 1962 J. M.REYNARD CONTROL MECHANISM 2 Sheets-Sheet 2 Filed March 9, 1961 INVENTORJOHN M Y United States This invention relates to a differential controImechanism, and more particularly relates to a novel type ofdifferentially operating device for positioning the printing head of amatrix printer, said device having an indexible output element and aplurality of control input members operatively connected to said outputelement and selectively operable in coded combinations for varying theextent of indexing movement of said output element.

In matrix type printing machines the printing head is successivelydisplaced through predetermined distances in order to serially bring therespective desired type to an Operative position at the printing pointof the machine. In this type of operation the means provided fordisplacing the printing head through variable strokes must partake of avery accurate high speed motion. The positioning mechanisms previouslyproposed or used for controlling such indexing motions of the printinghead of matrix machines have not always been satisfactory because ofbeing unreliable in accuracy, having inherent high inertia forces,and/or being too complex and expensive for practical purposes.

One object of the instant invention is to provide a reliably accuratedifferential positioning mechanism for efficiently indexing the printinghead of a matrix type printer.

Another object of the invention is to provide a novel motiontransmitting and control mechanism having an output shaft which isadapted to be driven by a plurality of serially interconnecteddifferential or epicyclic units which may be selectively operatedincoded combinations so as to cumulatively rotate said output shaft tovariable desired extents.

Anotherobject of the invention is to provide a novel positioningmechanism for the printing head of a matrix printer, said positioningmechanism comprising an output shaft which is adapted to be connected soas to be rotated by the collective action of a plurality ofinterference-fit 'ball type diiferential units that are selectivelyoperated in coded combinations so as to rotate said output shaft throughvarious predetermined angles.

Another object of the invention is to provide a novel positioningmechanism for matrix printers and the like whereby a plurality ofplanetary type differential units are serially connected together sothat the output means from each unit is connected to the drive inputmeans for the next unit, the respective control input means for theunits thereby being free to modify the, movement being transmitted bysaid differential units.

Other. objects and many of the attendant advantages of this inventionWill be .readily appreciated as the same becomes better understood byreference to the following detailed description when considered inconnection with the accompanying drawings in which like referencenumerals designate like parts throughout the figures therer FIGURE 4 isa schematic view of the mode of interconnecting the control elements ofthe instant apparatus.

Referring to FIGURE 1' there is shown a conventional type cylindricalmatrix printing head 10 having a circumferentially disposed anduniformily spaced array of type 11 mounted on the cylindrical peripherythereof. The head 10 is adapted to be rotatably indexed to successiveprinting positions by means of a positioning mechanism 12 that has anoutput shaft 13; the matrix head 10 being rotatably adjustably clampedon said output shaft 13 by any suitable means. A hammer 14, operativelymounted and connected so .as to be actuated by a solenoid 15, isprovided for cooperating in the usual manner with the various type 11 ofthe matrix printing head that are moved to the printing point of themachine so that various characters corresponding to said type may beprinted on a record sheet 16 through the medium of the inked ribbon 17.The type for one desired set of characters is located on a 180 arc ofthe periphery of the head 10 while the type for another desired set ofcharacters is located on the other 180 arc of the head periphery. Thehead 10 will be rotatably shifted 180 when a change in the charactersets to be used is desired. When using either set of type the type headis normally disposed in a central home position and is capable ofswinging up to substantially to six discreet printing positions oneither side of said home position.

The positioning mechanism 12 is generally comprised of four ball typedifferential or epi-cyclic units 20, 21, 22 and 23, FIGURES 1 and 2,which are operatively connected in series so as to form a cumulativemotion transmitting means for the outputrshaft 13. The four differentialunits are respectively operated by means of four control input arms 24,25, 26 and 27; these arms being selectively arcuately displaced in codedcombinations so as to cumulatively effect a predetermined rotation ofthe output shaft 13 and the matrix head 10. The lowermost differentialunit 20 includes a tubular hub 30 that is formed with an annular groove31 in which four planetary balls 32 are adapted to roll. Each ball 32 isclosely retained in one of four uniformly spaced apertures 33 formed ina ball retainer ring 34. An outer ring member 35 having an innercylindrical surface 36 is mounted over and surrounds the balls 32. Thethree basic ,elements comprising the first dilferential unit 20, namelyhub 30, balls 32 together with the ball retainer ring 34, and ringmember 35, are relatively radially dimensioned so that when they areassembled as shown in FIGURE 2 an interference fit exists. During thenormal operation of the positioning mechanism 12 the tubular hub 30remains rotatably fixed. When it is occasionally desired to shift thematrix head so that the secondset of type may be used the tubular hub ismerely rotatably indexed through an arcuate stroke sufiicient to producea 180 rotation of the said output shaft 13. The means to so index hub 30may comprise any suitable device, such as a one half revolution clutchor the like, which is diagrammatically illustrated at 37, 40 of FIGURES1 and 3. In normal operations however the tubular hub 30 will remainfixed and unless otherwise indicated it will be assumed during thesubsequent discussion of the operation of the instant apparatus thatthis normal condition exists. The ring member 35 is secured to saidradially extending control input arm 25 which in turn is biased by meansof a spring 43 into normal engagement with the fixed common bar stop 44.Arm 25 is adapted to be swung into engagement with and held againstafixed common bar stop 45 by means of a solenoid 46. As will be apparentwhen the hub 30 remains rotatably fixed a s'wingingmovement of the inputarm 25 will cause .the balls 32 to roll. around the grooved periphery ofhub 30 3 which in turn will cause the ball retaining ring 34 to rotateabout the axis of the unit. This differential type motion of unit 20will take place in a non-slipping manner due to the said interferencefit between the parts.

The ball retainer ring 34 is axially extended and is provided with asecond set of four uniformily spaced apertures 50 in which arerespectively disposed a second set of four closely fitting planetaryballs 51 which are adapted to roll around the annular grooved portion 52of a second hub 53. Hub 53 is formed with depending axial shaft portion54 which extends through the tubular hub 30 and to which is fixed saidcontrol input arm 24. The outer end of arm 24 is biased by means of aspring 55 into normal engagement with the bar stop 44 and is adapted tobe rotatably displaced into engagement with the bar stop 45 by means ofa solenoid 56. A second outer ring member 57 having a cylindrical innersurface 58 is mounted over and surrounds said planetary balls 51. Thethree basic elements comprising the second differential unit 21, namelythe hub 53, balls 51 together with the ball retaining ring, and the ringmember 57 are relatively radially dimensioned so that when they areassembled as shown in FIGURE 2 an interference fit exists. As will beapparent when the input arm 24 is pivotally displaced the resultantrotation of the hub 53 will be transferred to the balls 51 which in turntransmit this rotational movement to the ring member 57 in an amountdependent on whether or not the balls 51 are permitted by the ballretaining ring 34 to roll or just to rotate on their own geometric axes.Whether or not the ball retainer ring 34 rotates depends on whether ornot the input arm 25 has been operated as noted above. This differentialtype movement of unit 21 will take place in a non-slipping manner due tothe said interference fit between the parts.

The ring member 57 is axially extended and is provided with a reducedportion which is formed with an annular groove 60 and which defines thehub 61 of the third differential unit 22. A third set of planetary balls62 are mounted for rolling movement in the groove 60 and arerespectively closely fitted into the four apertures 63 formed in a thirdball retaining ring 64. A third outer ring member 65 having acylindrical inner surface 66 is mounted over and surrounds the balls 62.The ball retaining ring 64 is secured to the said control input arm 26.Arm 26 is biased by means of a spring 67 into normal engagement with thebar stop 44 and is adapted to be rotatably displaced into engagementwith and held against bar stop 45 by means of a solenoid 70. The threebasic elements comprising the third differential unit 22, namely hub 61,balls 62 together with the ball retainer ring 64, and the ring member 65are relatively radially dimensioned so that when they are assembled asshown in FIGURE 2 an interference fit exists. As will be apparent whenthe input arm 26 is pivotally displaced the resultant rotationalmovement of the ball retaining ring 64 will be transferred through balls62 to the ring member 65 in an amount dependent upon the rotationalmovement, if any, of the hub 61. The extent of rotation of hub 61 will,as noted above, be determined by whether or not the input arms 24 and/or25 have been operated. This differential type movement of unit 22 willtake place in a non-slipping manner due to the interference fit betweenthe parts.

The ring member 65 is axially extended and is provided with a reducedportion that defines the ring member 71 of the fourth differential unit23. The ring member 71 is formed with an inner cylindrical surface 72which is mounted over and surrounds a fourth set of four planetary balls73. Balls 73 are respectively closely fitted into a set of uniformlyspaced apertures 74 formed in a fourth ball retainer ring 75 and areadapted to roll around an annular groove 76 formed in a hub 77. Hub 77is integrally connected to the said output shaft 13 of the positioningmechanism and the ball retaining ring 75 is secured to the said controlinput arm 27. Arm 27 is biased by means of a spring 78 into normalengagement with the bar stop 44 and is adapted to be displaced intoengagement with and held against the bar stop 45 by means of a solenoid81. The three basic elements comprising the fourth ditferential unit,namely hub 77, balls 73 together with the ball retainer ring 75, and thering member 71 are relatively radially dimensioned so that when theparts are assembled as shown in FIGURE 2 an interference fit exists. Aswill be apparent when the input arm 27 is rotatably displaced theresultant rotation of the ball retaining ring 75 will be transmittedthrough balls 73 to th hub 77 and output shaft 13 in an amount which isdetermined by the extent of rotation, if any, of the ring member 71. Therotation of ring member 71 is as noted above determined by whether ornot the input arms 24, 25 and/ or 26 have been operated. Thisdifferential type movement of unit 23 will take place in a nonslippingmanner due to the said interference fit of the parts.

It will now be apparent that the matrix head 10, FIG- URE 1, may bemoved from a central home position to any one of several operativepositions by the selective operation of the various control input arms24, 25, 26 and 27 of the differential type positioning mechanism 12. Theratios of the diameters of the hubs, balls and rings of the differentunits 20-23 may be adjusted so that the desired sizes of angulardisplacements of the matrix printing head 10 occur in response to theoperation of the respective control input arms 24-27. By way ofillustration the effective relative diameters of the various parts maybe adjusted as follows.

Where D equals approximately /8 inch and each input arm is capable ofbeing displaced through an operative arcuate stroke of approximately 15the output shaft 13 and head 10 will be given substantially thefollowing clockwise and counter clockwise rotative dis placements by thenoted selective displacement of the control input arms 24-27.

Degrees of resultant rote.

tion of head 10 from nor- COntt'Ol input arms operated: mal central homeposition 25, 27 25, 27, 24 +75 27 +60 27, 24 +45 25 +30 25, 24 +15 none0 24 15 26, 24, 27- 30 26, 25 45 26, 24, 25 60 26 75 26, 2 90 Onediminuitive positioning mechanism 12 has been constructed wherein theoverall length is about 1.25 inches and the diameter of the largest oneof the cylindrical surfaces (66) is in the order of only /1 of an inch.As will be apparent the operation of such a small size mechanism willinvolve low inertia forces and such opera tions may occur at relativelyhigh speeds with a minimum of noise, vibration, etc.

In effect each of the differential units 20-23 has a drive input means,a control input means and an output means. The output means for onedifferential unit is connected to the drive input means of the nextdifferential unit; for .example, the output means (balls 32 and thelower portion of the ball retainer ring 34) for the differential unit 20is connected to the drive input means (balls 51 and the upper portion ofthe ball retainer ring 34) for the next differential unit 21, thecontrol input means for the units 20 and 21 being respectively definedby the ring 35 together with its associated control input arm 25 and thehub 53 together with its associated control input arm 24. In similarfashion the output means (ring member 57) of the differential unit 21 isconnected to the input drive means (hub 61) of the differential unit 22,the control input means here comprising the balls 62 and the ballretaining ring 64 together with the associated control input arm 26. Inturn the output means (ring member 65) of the differential unit 22 isconnected to the input means (ring member 71) of the differential unit23, the balls 73 and ball retainer ring 75 together with the controlinput arm 27 here constituting the control input means for thedifferential unit 23. Although the differential units 20-23 areinterconnected in series in the functional sense that the output meansof one unit is connected to the drive input means of the next unit, whatparticular element of a differential unit constitutes the drive inputmeans, the control input means or the output means for that particulardifferential unit may vary. For example, the hub of one unit mayconstitute the drive input means for that unit while the hub of the nextunit may be an output means for this next unit. Conversely for example,the control input means for one unit may constitute the ring member ofthat unit while the control input means for the next unit may constitutethe planetating balls and retainer of this next unit. Thus any one ofthe basic parts or elements of any given diiferentialunit may bestructurally connected to any one of the elements of the next unit.Further the mode of interconnecting a first to a second differentialunit may differ from the mode of interconnecting the second to a thirddifferential unit.

the operation of the instant apparatus. Five bails 101, 102, 103, 104and 105 are pivotally mounted by any suitable means on the machine sideframes and respectively have laterally swingable body portions 106, 107,110, 111 and 112 which extend "across the machine and beneath the normalcomplement of key levers such as 113. Bails 101-105 are yieldablymaintained in their normal FIGURE 4 positions by any suitable springmeans and upon counter clockwise displacement are adapted to close therespectively associated normally open switches 114, 115, 116, 117 and118 which are respectively proximate to said bails and which aresuitably supported on the machine frame. Switches 114-117 areelectrically connected so as to respectively control the operation ofsaid solenoids 56, 46, 70 and 81 which respectively actuate said inputarms 2427. The switch 118 is electrically connected so as to control theoperation of the hammer solenoid 15. Each key lever is provided with asimilar short depending catnming tooth 120 and in addition is providedwith a coded number of longer camming teeth 121. The teeth 121 areadapted to arcuately displace the respective adjacent associated bailsand thereby close the related switches in response to the selectivedepression .of the key levers.

In operation after any given coded combination of switches 121 have beenclosed and the related control input arms have been thereby actuated toproperly position the matrix head the relatively short tooth 120 of theFIGURE 4 shows an exemplary means for controlling to print the desiredcharacter on the record sheet 16. It will be apparent here that due tothe relative shortness of tooth 120 no printing action will occur untilafter the positioning mechanism 12 has displaced matrix head 10 to thedesired indexed position. having different coded numbers and positionsfor teeth= 121 are successively depressed, different type 11 will besequentially brought to printing position by the action of thedifferential positioning mechanism 12.

When the second set of type on the other 180 half of the periphery ofhead 10 is to be used the shift means 37, 40 are operated to therebydisplace the head through 180 from the normal home position to analternate home position. Thereafter the selective operation of thecontrol input arms 24-27 will serve to bring the various type of thissecond set to printing positions in a manner similar to that abovedescribed for said first set of type 11 to be used.

If after prolonged use of the instant apparatus a slight amount ofslippage has occurred between the various parts of the differentialpositioning mechanism 12 then the matrix head 10 may be unclamped fromthe output shaft 13, rotatably adjusted to proper phase relation andthen reclarnped on said output shaft 13. Thereafter all the type 11 andall the differential units will again be in proper phase condition. Itwill be apparent that conventional type gears may be used in place ofthe various balls, ring members and hubs; and that a similardifferential positioning mechanism can be correspondingly used tocontrol an axial shifting movement of the matrix head 10 where more thanone circumferential band or row of type 11 is to be mounted on saidmatrix head.

The instant mechanism 12 has been shown and described here as apositioning means for matrix printers; however it may be utilized inseveral other applications with equal facility; for example, themechanism may be employed as an arithmetic unit wherein movement of theoutput shaft 13 represents an algebraic sum of quantities represented bythe displacements of the control input arms 2427. Also it will be notedthat the time displacement characteristics of the motion of any one ofthe control input arms 24-27 will produce correspondingtime-displacement characteristics in the resultant effects on themovement of the output shaft 13. Further the unit or mechanism 12 may beused simply as a motion transmitting means wherein a fixed or variableamplification or reduction of an input movement is desired.

While there is in this application specifically described one form whichthe invention may assume in practice,

it will be understood that this form of the same is shown for purposesof illustration only and that the invention may be modified and embodiedin various other forms without departing from its spirit or the scope ofthe appended claims.

The invention claimed is:

1. In a printing device; a matrix printing head, a plurality of typemounted on said matrix head, means for creating a printing pressurebetween said head and a record sheet that is to be printed on, apositioning mechanism for sequentially variably positioning said matrixhead, said positioning mechanism comprising a plurality of coaxiallyarranged differential units which are effectively serially connectedbetween each other and said matrix head, each of said differential unitsincluding a hub element, a pluarity of planetating elements adapted toroll around said hub element, and an output element, a control input armoperatively connected to one of the elements of each of saiddifferential units, and control means for selectively operating saidinput arms,

2. A position mechanism for matrix printers and the like; comprising aplurality of differential type units, a first one of said units havingthree basic parts namely a hub portion, at least one rollable element,and an outer member, one of said parts constituting an output means forsaid unit, a second one of said parts constituting a As different keyleversv drive input means for said unit, and the third one of said partsconstituting a control input means for said unit, a second one of saidunits also including three basic parts that are respectively similar tothose of the first differential unit, a third one of said units alsoincluding three basic parts that are respectively similar to those ofsaid first unit, the output means of the first differential unit beingconnected to the drive input means of said second differential unit andthe output means of said second differential unit being connected to thedrive input means of said third differential unit whereby selectiveoperation of the three control input means for said units will causevariable displacements for the output means of said third differentialunit, the mode of interconnecting said units being such that connectionbetween the parts of said first and second differential units isdifferent from the connection between the parts of said second and thirddifferential units.

3. Apparatus as defined by claim 2 wherein in at least one of saiddifferential units, the hub portion is defined by a cylindrical member,the rollable element is a ball, and the outer member is a ring memberwhich surrounds said balls and hub portion, and wherein said parts whenassembled have a radial interference fit so as to thereby make possiblea non-slipping connection therebetween.

4. A positioning mechanism for matrix printers and the like; comprisinga first differential unit having three basic parts namely a hub portion,at least one rollable element and an outer member, one of said partsconstituting an output means for said unit, a second one of said partsconstituting a drive input means for said unit, and the third one ofsaid parts constituting a control input means for said unit, a seconddifferential unit which also has three basic parts that are respectivelysimilar to those of said first differential unit, the output means forsaid first unit being connected to the drive input means for the secondunit such that the individual actuation of the control input means foreach of said units will respectively produce different rotativedisplacements of the output means of said second unit.

5. Apparatus as defined by claim 4 wherein the output means for thefirst differential unit is defined by a different one of the three basicunit parts than the output means for said second differential unit.

6. Apparatus as defined by claim 5 wherein the control input means forthe first unit is defined by a different one of said basic parts thanthe control input means for said second unit.

7. Apparatus as defined by claim 5 wherein the output means of the firstdifferential unit comprises the rollable element of said firstdifferential unit, and the drive input means of the second differentialunit comprises the rollable element of said second differential unit,

8. Apparatus as defined by claim 5 wherein the output means from thefirst differential unit comprises the outer member of said firstdifferential unit, and the input drive:

means from the first differential unit comprises the outer member ofsaid first differential unit, and the drive input means of the seconddifferential unit comprises the outer member of said second differentialunit.

10. Apparatus as defined by claim 5 wherein the roll-- able element ofat least one of said differential units com prises a ball that isadapted to roll along the respective effective outer and inner surfacesof the associated hub portion and outer member, these three basic partsof said one differential unit being relatively dimensioned and assembledso as to have a non-slipping interference fit therebetween.

11. In a printing device; a matrix printing head, a plurality ofprinting type mounted on said matrix head and adapted to be selectivelymoved to a predetermined printing point, means for creating a printingpressure between the selected type located at said printing point and arecord sheet that is to be printed on, a positioning mechanism forvariably displacing said matrix head so as to successively bringdifferent type to said printing point, said positioning mechanismcomprising a plurality of coaxially arranged differentially operatingunits which are serially interconnected, each unit having a hub element,at least one planetating element adapted to roll around said hubelement, and an output element all interconnected so as to form adifferentially operating unit, a control arm connected to one of saidelements in each of said units, each control arm being movable torotatably displace said matrix head to a predetermined extent, and meansoperable to sequentially actuate different coded combinations of saidcontrol arm.

12. Apparatus as defined in claim 11 wherein at least one of saiddifferentially operating units includes a hub, a plurality of balls andan outer ring member, said balls adapted to frictionally engage and rollaround the outer and inner peripheries of the associated hub and ringmember respectively.

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